how to update cached dictionary values in c#

Question

 

hi guys,

 

 below code  i am caching   dictonary values. i have one doubt if  cached dictionary value changed backend how to update the value here( here i am caching value 20 mins suppose if they update i need to update cached value right)   please help on me guys

 

  

 

Dictionary<string, string> Cache = new Dictionary<string, string>();

var cache = new Cache<string, string>();

// Cache.Add(dictionaryItem.Phrase,TimeSpan.FromMinutes(25))

cache.Store(dictionaryItem.TemplateId.ToString(), dictionaryItem.Phrase, TimeSpan.FromMinutes(20));

// Console.WriteLine();

return dictionaryItem.Phrase;

/////////////

 

public class Cache<TKey, TValue>

{

private readonly Dictionary<TKey, CacheItem<TValue>> _cache = new Dictionary<TKey, CacheItem<TValue>>();

public void Store(TKey key, TValue value, TimeSpan expiresAfter)

{

_cache[key] = new CacheItem<TValue>(value, expiresAfter);

}

public TValue Get(TKey key)

{

if (!_cache.ContainsKey(key)) return default(TValue);

var cached = _cache[key];

if (DateTimeOffset.Now - cached.Created >= cached.ExpiresAfter)

{

_cache.Remove(key);

return default(TValue);

}

return cached.Value;

}

}